Process of inhibiting corrosion and corrosion inhibiting compositions



United States Patent v, v 2,935,474 PROCESS OF INHIBITING CORROSION AND CORROSION INHIBITING COMPGSITIONS Willard I-I. Kirkpatrick, Sugar Land, and Virgil L. 'Seale, Houston, Tex.,' assiguors to 'Visco' Products Company, 7 Houston, Te x., a corporation of Delaware I NoDrawing. Application November 28 1955 Serial No. 549,553

7 Claims. Cl. 252-855,

wells, refineries or the like.

Still a further object of the invention is to provide a :method of inhibiting corrosion of metals in systems which are subject to contact by various corrosive agents such as carbon dioxide, aqueous or non-aqueous solutions of carbon-dioxide, hydrogen sulfide, aqueous or nonaqueous solutions of hydrogen'sulfide, brines, weak inorganic acids and organic acids.

An additional object of the invention is to provide new and improved corrosion inhibitingcompositions which are readily absorbed by metal surfaces. Other objects will appear hereinafter.

In accordance with the invention, it has been found that new and improved results in inhibiting corrosion,

particularly in inhibiting the corrosion of ferrous metals in oil and gas well equipment, areobtained by applying to the metals a corrosion inhibitor which can be described as a quaternary salt of a compound from the group consisting of'eompounds having the general formula 12-0 NHO.H,,),,.NH,

and compounds having the general formula Nn, c.HaNn 1R- (NRO s ub-NH:

wherein x, y, m and n are the same or different whole numbers, and R is the non-carboxy portion of a fatty acid containing at least 12 carbon atoms.

The compounds to be quaternized are preferably produced'by heating to a temperature of at least 260 C.

under conditions facilitating the elimination of an aqueous distillate, a mixture comprising an alkylene polyamine and an organic acid from the group consisting of fatty acids and dimeric derivatives of fatty acids, said fatty acids having at least 12 carbon atoms.

The quaternary salt of the aforementioned compound is generally produced by admixing with the compound an alkyl ester of a mineral acid, preferably by admixing fwith the compound lower alkyl esters of a strong acid, ,such as the lower alkyl halides, sulfonates and sulfates,

e.g., diethyl sulfate, in an amount in excess of molecular requirements. Employing an excess of diethyl sulfate as the quaternizing agent,;the reaction is believed to be as follows:

wherein Ris the non-carboxy portion of a detergent. forming fatty acid containing 12-or more carbon atoms, and n and x are whole numbers. However, in the above representative reaction, it is not certain that 'all of'the nitrogen groups are ethylated; nor is it certain that only one of the ethylated nitrogen groups is quaternized.

The simplest polyamines employed for the practice of The alkylene polyamines which are preferably employed in preparing the corrosion inhibitors of the present invention include, for example, diethylenetriamine,

triethylenetetramine, tetraethylenepentamine, dipropylenetriamine, tripropylenetetramine, and higher. homo logues thereof, including still residues that remain after the preparation of these materials. These starting .ma-

terials can be described generally as polyalkylene polyamines because they contain two or more alkylene group's separated from each other by nitrogen atoms,

The terminal amino groups of the alkylene polyamines are preferably primary amino groups and any intermediate amino groups (or imino groups) are preferably secondary. In an amidification reaction the acylation of the polyamine can take place either at the primary or secondary groups, but acylation preferentially occurs at the primary groups until these groups are acylated. When the primary amino groups are blocked by the acyl groups or other groups, acylation or amidification occurs at the secondary amino groups.

' The organic acids suitable for the purpose of this in vention are fatty acids having at least 12 carbon atoms or the dimeric derivatives thereof. Mixtures of fatty acids may also be used. An example of such a mixture is crude tall oil in which the fatty acids comprise 45% to 60%] V by weight and include, oleic, linoleic and dilinoleic acids, the remainder being largely natural carbocyclic resin acids, principally abietic acid. Castor oil is another material containing suitable fatty acids.

The dimeric derivatives of fatty acids suitable for the purpose of this invention are the condensation products of dimers of two molecules of fatty acid. Any mixtures of the dimers with the monomeric acids or mixtures of dimeric acids are also suitable. Dimers of suitable" fatty acids are obtained, for example, as a by-product from the production of sebacic acid. Dimeric acids suitable for use as starting materials in the practice of the invention can be prepared by any of the methods described in Goebel, US. 2,482,761, or Landis, US. 2,632,695. Especially suitable polymer acids for the purpose of the invention are polymerized di-unsaturated mono-carboxy acids, e.g., dilinoleic acid, and the dimeric acids obtained by the dry distillation of castor oil in the presence of sodium hydroxide. I

The fatty acid chlorides, g'lycerides and other esters of the fatty acids may bev used in place of the free fatty acids, but this is not usually done in' commercial practice.

Generally the condensation of the polyaminewith the 2,935,414 Patented May 311 3 while inexcess of a mol ratio of N:COOH of 1:1, usually do not exceed a mol ratio of NzCOOH of 20:1.

The invention is further illustrated but is not limited by the following examples in which quantities are stated in parts by weight unless otherwise indicated. Some of the starting materials employed in these examples are defined as follows:

Polyamine H Special is a mixture of 75% polyalkylene polyamine homologues higher than tetraethylenepentamine and 25% of diethylenetriamine.

Technical diethylenetriamine is a mixture of 85% diethylenetriamine and 15% higher polyalkylene polyamine homologues.

VR-l acid is a mixture of polybasic acids, with an average molecular weight of about 1,000. It has an average of slightly less than two carboxylic acid groups per molecule. It is a lay-product acid, and is a dark amber, rather viscous liquid. A typical sample of VR-1 acid gave the following analysis:

Acid number 150 Iodine number 36 Saponification number 172 Unsaponifiable matter percent 3.7, 3.5 Moisture content do 0.86

Dimer acids are a commercial form of a dimeric polymer consisting essentially of dilinoleic acid. The method used in their preparation is set forth in the Journal of the American Oil Chemists Society, 24, 65 (March 1947). Specifications are as follows:

Hardesty 401 fatty acid is a by-product from the production of sebacic acid which contains between 40% and 50% dimer acids. The molecular weight as determined from the saponification number is around 300. The material contains approximately 75 to 80% of free fatty acid and has an iodine number of 50 and a saponification of 180.

Hardesty D75 acid is a dimerized fatty acid derived from the manufacture of sebacic acid. It differs from Hardesty 401 fatty acid in that most of the monobasic acids have been removed. It is essentially a clear dimerized fatty acid with an average equivalent weight of about 300.

Example I 2580 pounds of crude tall oil and 1375 pounds of polyamine H Special are charged into a stainless steel vessel equipped with a means of heating and agitation, and a trap for removing Water collected during azeotropic distillation. The reaction mass is agitated while gradually heating. At a temperature of 130-140 C. extreme care is exercised, for the presence of any contaminating water in the reactants will cause severe foaming in the vessel. Heating is continued to 260-275 C. and held at that point for at least thirty minutes until about 32 gallons of aqueous distillate is secured. The reaction product is represented by the formula:

wherein R is the non-carboxy portion of a fatty acid obtained from tall oil, and x and m are the same or different whole numbers. The reaction mass is then cooled to about 90 C. At this point 2120 pounds of diethyl sulfate are added gradually in small portions of 100 to 200 pounds each, being certain that the reaction temperature is maintained below 120 C. After the addition of diethyl sulfate has been completed, the temperature of the mass is raised to 140 C. and held at that point for one hour. After cooling to C., 4050 pounds of water and 2900 pounds of methanol are added and the product stirred to uniformity to yield the finished product.

Example II In a three-necked reaction'flask there is added 300 parts by weight of tall oil and parts by weight of a technical grade diethylenetriamine. Thereaction flask is provided with a means of agitation, heating, and a water trap to remove aqueous distillate as it forms throughout the course of the reaction. Temperature isgradually raised and at C. an aqueous distillate begins to form. After four hours at a maximum temperature of 255 C. a total of 32 ccs. of aqueous distillate was secured. The reaction product is represented by the formula:

wherein R is the non-carboxy portion of a fatty acid obtained from tall oil. After cooling to approximately 90 C., 250 grams of diethyl sulfate were added in small portions while maintaining the reaction temperature be low 100 C. After addition was complete the temperature was raised to 135 l40 C. and held for one hour. After cooling to approximately 90, 375 grams of water and 250 grams of methanol were added with stirring to yield the finished product.

Example I Il Following the procedure of Example II, 60 grams of anhydrous ethylene diamine are used in place of the technical grade diethylenetriamine. Prior to quaternizing the reaction product is represented by the formula:

wherein R is the non-carboxy portion of a fatty acid obtained from tall oil.

Example IV Following the procedure of Example II, 80 grams of a 90% to 95% propylene diamine are used in place of the technical grade diethylenetriamine. Prior to quaternizing the reaction product is represented by the formula:

wherein R is the non-carboxy portion of a fatty acid obtained from tall oil.

Example V Following the procedure of Example II, grams of tetraethylenepentamine are used in place of the technical grade diethylenetriamine. Prior to quaternizing the reaction product is represented by the formula:

wherein R is the non-carboxy portion of a fatty acid obtained from tall oil.

Example Vl Following the procedure ofExample H, 280 grams of oleic acid were used in place of the crude tall oil. Prior to quaternizing the reaction product is represented by the formula:

Example VII Following the procedure of Example 11, 312 grams of castor oil are used in place of the crude tall oil. Prior to quaternizing the reaction product is represented by the formula given in Example 11 except that R is the non- I The quantity amen-'4 ear-boxy portion of a fatty acid obtained fronticastor Example VIII Eollowing theprocedure of Example II, 300 grams of Hardesty D75 acid were used in place of the tall oil. Prior to quaternizing the reaction product is represented by theforrnula:

wherein R is the non-carboxy portion of a vdimerizedfatty acid derived from the .manufactureof sebacic acid.

Example IX Following the procedure of Example II, :500 grams of Emerys dirnerized fatty acid are used in place of the crude talloil. I i

Example XI I Following the procedure of Example-II, 300 grams of Hardestys No. 401 fatty acids are used in place of the crude tall oil.

- Example XII Following the procedure of Example II a mixture of 150 grams of Hardesty D75 acid and 75 grams of crude tall oil were used in place of the crude tall oil alone.

The compositions prepared in Examples I-XII were found to be highly surface'active. They were not only effective'as corrosion inhibitors but also had a bactericidal action. v

of the active efiective corrosion inhibitor requiredto retard or prevent corrosion is very small,

, being ofthe'order of a molecular film on the iron metal surface or other'metal surface to .be protected. In order to properly distribute'lthe corrosion inhibitor on the metal surface, it is preferably dispersed in an inert solvent such as'methanol, as directed in Examples I-XIL the so-called solid stick corrosion inhibitors.

The .invention is specially useful in combating internal corrosion attack in oil and gas wells, flow lines, and other oil production installations. Its use is also applicable in the protection of secondary recovery installa- ,tions such as supply and injection wells. The process of the invention is carried out simply by bringing the'c'orrosion inhibiting composition in contact with the metal surface of. the'equipment. The preferred method is to inject a corrosion inhibiting composition of the type dissolved in an inert inorganic solvent into the well annulus by means of a chemical proportioning pump continuously 'at the rate of one quart to two quarts of the aforesaid compositions per wellper day. A'ratio of 10 parts to 200 parts (preferably 50 parts) per million of the composition based on total production is usually YCOIIL mended as a ratio which will bring corrosive attack under control in the down-hole treatment of oil wells. One quart of the composition per two million cubic feet of gas produced in the recommended dosage for gas wells, although the dosage should be somewhat controlled by the amount of water produced. When treatment is initiated, it is general practice tovbatch treat with to gallons of a methanol dispersed composition to take advantage of the detergent properties of the composition and also to establish a high concentration of the composition at the onset of treatment. .An alternative method is to inject a slug of the material into the well periodically Where the corrosion inhibiting composition is prepared as a solid,it-can be dropped:

over one or two days.

into the well as a solid lump. Any-of the other well known methods for applying corrosioninhibiting materials to oil and gas wells'canbe used 'inthepractice of the invention. v 1

The corrosive fluids which may be treated in the practice of the invention "include hydrocarbon fluids'icontaining water such as, for example, crude petroleum as it comes from the well, petroleum distillates such. fuel i v acid groups in the molecule assists in providing better adsorption and larger coverage of the metal surface which is to be protected against corrosion. i I

While the invention is .not limited to1any theory, it is thought that the unusual effectiveness of these compositions in inhibiting corrosion is due to their high oil solubility, the fact that they cause the oilto wet the metal surface and the fact that they are not lost in the water phase in the :fluid containing both oil andw'ater.

It will be understood that the invention isssusceptible to some variation and modification. Thus, the quaterniz ing reaction can be driven more nearly to completion :by removing the free acid formed. This can be accomplished by adding a basic materialduring the" course of I:

the reaction as, for example, sodium hydroxide orspotassium hydroxide. Good results are obtained when the final pH of the reaction mixture is between 6 'and 7. rlfxthe pH falls below 6 an additional quantity of the polyamine or of the amide-amine'can be added in order to raise the a 7 pH. When the quaternizing action isnotdriven itocompletion some simple amine saltscan be formed. For

be replaced by an ethyl radical, the resultant product has the following chemical formula:

However, the possibility exists for the formation of minor amounts of compounds having the following chemical 1 formulae:

H CIHI R-C-Ik-CalL-N H mm 02H! R-(HI-ILFFCQHI It will be apparent that when diethylenetriamine is employed in place of ethylenediamine as the polyamine a greater number of derivatives can be formed. The same is true when any other polyalkylene polyamine is substituted for an alkylene diamine because the polyalkylene polyamine contains secondary amino nitrogen atoms which are capable of reacting with the quaternizing agent.

The invention is hereby claimed as follows:

1. A process for preventing corrosion of ferrous metals in contact with petroleum hydrocarbons containing corrosive agents selected from the group consisting of carbon dioxide, hydrogen sulfide, brine, weak inorganic acids and organic acids, which comprises applying to the metal a corrosion inhibiting amount of a composition comprising a quaternary salt of at least one compound from the group consisting of compounds having the general formula and compounds having the general formula NH:(C.H:,NH)..(fi-B fi (NH 0 ,,Hg,,),,NH1

wherein x is an integer from 2-10, inclusive, y is an integer from 2-10, inclusive and m and n are at least 1 and R is the non-carboxy portion of a fatty acid containing at least 12 carbon atoms.

2. A process for preventing corrosion of ferrous metals in contact with petroleum hydrocarbons containing corrosive agents selected from the group consisting of carbon dioxide, hydrogen sulfide, brine, weak inorganic acids and organic acids which comprises applying to the metal a corrosion inhibiting amount of a composition consisting essentially of a quaternary salt of a compound produced by reacting an alkylene polyamine with an organic acid from the group consisting of fatty acids and dimeric derivatives of fatty acids at a temperature of at least 260 C. with the removal of water from the reaction mixture until about one mol of water of reaction per mol equivalent of carboxy groups have been removed, said acids having at least 12 carbon atoms.

'3. A process for preventing corrosion of ferrous metals in contact with petroleum hydrocarbons containing corrosive agents selected from the group consisting of carbon dioxide, hydrogen sulfide, brine, weak inorganic acids and organic acids which comprises applying to the metal a corrosion inhibiting amount of a composition consisting essentially of a quarternary salt of an acyclic compound produced by heating to a temperature of at least 260 C. with the removal of water from the reaction mixture until about one mol of water of reaction per mol equivalent of carboxy groups has been removed, a mixture comprising an alkylene polyamine having at least two and not more than ten carbons per alkylene group and an organic acid from the group consisting of fatty acids and dimeric derivatives of fatty acids, said acids having at least 12 carbon atoms.

4. A process for preventing corrosion of ferrous metals in contact with petroleum hydrocarbons containing corrosive agents selected from the group consisting of carbon dioxide, hydrogen sulfide, brine, weak inorganic acids and organic acids which comprises applying to the metal a corrosion inhibiting amount of a composition consisting essentially of a quaternary salt produced by heating to a temperature in the range of 260 C. to about 275 C. with the removal of water from the reaction mixture until about one mol of water of reaction per mol equivalent of carboxy groups has been removed, a mixture comprising an alkylene polyamine having at least two and not more than ten carbons per alkylene group and an organic acid from the group consisting of fatty acids and dimeric derivatives of fatty acids, said acids having at least 12 carbon atoms, and quaternizing the resulting product by admixing therewith a molar excess of an alkyl ester of a mineral acid.

5. The process according to claim 1 wherein said or ganic acid is a tall oil acid.

6. The process according to claim 1 wherein said organic acid is a dimerized fatty acid obtained as a byproduct of the manufacture of sebacic acid.

7. A process for preventing corrosion of ferrous metals in contact with petroleum hydrocarbons containing corrosive agents selected from the group consisting of carbon dioxide, hydrogen sulfide, brine, weak inorganic acids and organic acids which comprises applying to the metal a corrosion inhibiting amount of a composition consisting essentially of a quaternary salt produced by heating to a temperature in the range of 260 C. to about 275 C. with the removal of water from the reaction mixture until about one mol of water of reaction per mol equivalent of carboxy groups has been removed, a mixture comprising a polyalkylene polyamine having 2-3 carbons per alkylene group and two primary amino groups and tall oil, and quaternizing the resulting product by admixing a molar excess of diethyl sulfate therewith at a final pH between 6 and 7.

References Cited in the file of this patent UNITED STATES PATENTS 2,468,163 Blair et a1 Apr. 26, 1949 2,583,772 Gunderson Jan. 29, 1952 2,598,213 Blair May 27, 1952 2,644,003 Gysin et al June 30, 1953 2,686,795 Koebner Aug. 17, 1954 2,691,631 Metler Oct. 12, 1954 2,720,490 Oxford Oct. 11, 1955 2,721,175 Lytle Oct. 18, 1955 2,742,498 Smith et a1 Apr. 17, 1956 2,763,612 Raifsnider et al Sept. 18, 1956 

1. A PROCESS FOR PREVENTING CORROSION OF FERROUS METALS IN CONTACT WITH PETROLEUM HYDROCARBONS CONTAINING CORROSIVE AGENTS SELECTED FROM THE GROUP CONSISTING OF CARBON DIOXIDE, HYDROGEN SULFIDE, BRINE, WEAK INORGANIC ACIDS AND ORGANIC ACIDS, WHICH COMPRISES APPLYING TO THE METAL A CORROSION INHIBITING AMOUNT OF A COMPOSITION COMPRISING A QUANTERNARY SALT OF AT LEAST ONE COMPOUND FROM THE GROUP CONSISTING OF COMPOUNDS HAVING THE GENERAL FORMULA. 